Adding N03 to reduce P04 via macro growth.

[DennisRB]

A lot of people said I was crazy when I started adding N03 to my planted FW aquarium to reduce algae. But the results speak for themselves. The plants are able to continue growing and absorb any P04, making P04 the limiting nutrient for algae/plant growth.

With P04 being the limiting nutrient instead of N03, the algae stays away. (note: you would only do this if you already have a zero N03 reading)

Most reef tanks have more ways to reduce N03 than they do for P04 removal. (sand beds live rock all reduce N03 but leave P04) This would suggest that a lot of tanks with nuisance algae have N03 as the limiting nutrient for algae growth. If this is the case any macro used for nutrient export may not be able to reduce P04 further.

So would it be possible to reduce nuisance algae in a reef tank by making P04 the limiting nutrient by adding small amounts of nitrate to allow macro's in the fuge to absorb the available P04? Has anyone tried this?

[Samala]

People who said you were crazy for adding nitrate, or micronutrients, CO2, more light, chelated iron, etc etc for a freshwater tank to compensate for PO4 were the ones being silly. Its an established practice.. any decent freshwater planted website, and certainly the APD, would have advised you to do the same. Nutrient uptake and ways to provide them are pretty well established in the freshwater crowd.

I would agree at first that adding nitrate would seem to help out with PO4 uptake.. but a wiser person who somtimes visit this board would advise you that not all the nitrate you add, or all the PO4 that disappears, would be due to macroalgae uptake.. it could also be through precipitating out in saltwater by binding with various compounds.

However, yes, I'd call adding nitrate to keep the plants growing strongly to take up your extra phosphate a winning idea. The plants need far more nitrogen than they do phosphorus, at least IME. In an environment where nitrogen is in high competition.. as you stated between the DSB, LR and plants/algae, it could easily be the limiting factor. (Potassium, which is another well established macronutrient in freshwater, is a blurry picture right now. As is most of the micro's such as iron or magnesium.)

As far as it excluding your nuisance algaes altogether.. hard to say. I dont think we have enough of a handle on nutrient dynamics and algae competition to say for sure. I know in my tank I get nuisance algae blooms when one or more factors are off.. phosphate too highly dosed.. pH is off... alkalinity a little unstable.. etc. Otherwise, the grasses grow beautifully and I have barely enough green glass algae to keep the snails happy. I havent tried to dose ammonium to see if it sparks an outbreak as you might expect in freshwater.

But I actually dose PO4, the micros, nitrates, etc., as I have no bioload to truly speak of.

Keep the ideas coming Dennis... Having another person to talk this through with, and come up with some reasonable ideas to test out.. will help immensely long term with the use of macro in our tanks, whether for display or more utilitarian purposes.

>Sarah

[DennisRB]

Thanks for your insight

Since my algae refugium has only been set up for a couple of weeks all the macro is growing well (despite having undetectable N03 and P04 before starting it up). But I expect that it will suck all the available N03 up eventually. When I start to see a decline in growth I might experiment by adding enough potassium nitrate to raise levels by 0.5 PPM.

[HippieSmell]

I agree with Samala

[DennisRB]

Do you have any pics of your tank Samala?

[Samala]

I have a whole progression of the tank as a ten gallon and I'm just about to put up the new pics for the twenty gallon.. hit my red house to see the website.

>Sarah

[jmperez32]

So would it be possible to reduce nuisance algae in a reef tank by making P04 the limiting nutrient by adding small amounts of nitrate to allow macro's in the fuge to absorb the available P04? Has anyone tried this?

Yes, I'm doing it.

Reading this post make me feel good … I am not so crazy.

First of all, I will like to apologize for my English; I'm from Spain, I'm a frequent reader of RC but I am not used to write in English. I will do my best … sorry If I don’t express well.

For several months I was unable to stop the algae bloom in my aquarium, even with zero nitrate and phosphate (I’ve got very few bioload). I tried almost every thing that could be suggested, but nothing worked. I’ve got several years of experience and some reefs aquariums that work really well for years, some of them with high nitrate levels.

I had macro (caulerpa racemosa and prolifera), but it did not grow, so I thought the problem was the nitrate. The first step was stopping the skimmer, buy it also raise the phosphate level, actually after two months nitrate were never detected (lower than 0.2 ppm), while phosphate raised till 0.3 ppm. But I get something, after several months of monochromatic brown colour (diatoms), I could see same green, but most of then cyanos, and the macro still didn’t grow.

I read something about the Readfield proportion (a relation between the ratio of nitrate and phosphate and the algae growth in soft water). I could not find anything equivalent for salt water, but I think it should be similar.

I’ve been adding nitrates (potassium nitrate) for some weeks now, in an effort to reduce de nuisance algae, increasing the ratio between nitrate and phosphate (Right now there are 2-3 ppm of nitrate and less than 0.1 ppm of phosphate). Until now I can’t say that the experiment has been a success, cyanos are still there but I observe a slow growth of macro algae.

Probably the problems are due to the old LR that I take from the other aquariums. I haven’t tried cooking the rook, before I will try to solve the problem this other way.

Greetings from the sunny Spain .

[DennisRB]

Good on you for giving it a go jmperez. I'm not sure if it is going to work for you since you already have a small N03 reading. I was only suggesting it with a zero reading. Do you have strong lighting for your macro? I recently had hair algae, diatom and cyano prob. I used sugar to clear it up, the nutrients have lowered so much that my macro has stopped growing too. All the bad stuff is gone now, so this stoped me trying out adding the N03. I have to get some for my planted tank anyway, so I might try it then. I have to get the macro growing again.

Sarah, thats a great page you have. I will keep an eye out for updates

[jmperez32]

I'm not sure if it is going to work for you since you already have a small N03 reading

... but never before adding NO3.

I never had nitrate reading before adding KNO3, I mantain this 2-3 ppm adding nitrate every day, if Istop adding it, it will go back to 0.0 in a few days.

3 ppm Nitrates per 0.1 ppm Phosfates gives an optimun RedField proportion for minimun algae growth.

[Samala]

JM - Very interesting! (Oh, and your english is great!! You should hear/read my spanish! I work with a guy from Argentina and he thinks my spanish is hilarious.)

I cant seem to find a reference for redfield ratio being applied to algae growth in softwater.. could you link it for me? I had first read about it being applied to nutrient content in phytoplankton in the ocean. Its a big topic and applied in many systems though.

Do you have a big DSB as well as the LR JM? I'm just trying to get a feel for how much live sand, live rock and macroalgae you have in your tank.

Also, I'm not sure we need to quibble about having zero nitrate readings before adding in any nitrate. I mean it makes sense to be sure that your system is sucking down nitrate that your fish produce before adding in more... but it you have a low level of nitrates, and relatively high phosphates, you could still end up with a problem with phosphates if the macro's dont get enough N to grow. Right? Anything less than 5ppm nitrate I personally add more. I dont trust the phosphate test kit I have really.. not lately.. but I keep that around .3ppm if I can.

Keep in mind I only have a few inverts still. And I'll try to finish the stinkin update on the website this week. My research has gotten to be overwhelming - I'm never home when the tank lights are on!

Great work JM - thanks so much for posting
>Sarah

[jmperez32]

Thank Samala,

I cant seem to find a reference for redfield ratio being applied to algae growth in softwater.. could you link it for me?

I found this article "Free of algae with RedField Ratio"

Do you have a big DSB as well as the LR JM? I'm just trying to get a feel for how much live sand, live rock and macroalgae you have in your tank

I had a DSB, but I thought that it could be cause of the algae, so I take out all the sand and right now it's a BB. Very few macroalgae remaind after several month of cyanos domination, but there is still some. I'm cheking it, if it grow I will add more.

[DennisRB]

Ok JM, sorry I thought you said that you did have a small N03 reading before you started adding more. Do you add iron?

[jmperez32]

Do you add iron?

Never try, I'm not sure abuot it. Does it improve the algae growth? How to dose it?

[DennisRB]

Iron is more often an algae growth limiting nutrient than N03 or P04 and is essential for algae growth. So chances are your algae is being limited by iron. Many people that use macro algae as nutient export on this board add iron to keep it growing. I use an iron based phosphate remover so my iron levels should be OK.

You can buy the additive at any fish store, its mainly used for freshwater planted tanks. As for dosing etc, I think Sarah would be able to help you out better than me. You should probably get an iron test kit first.

[jmperez32]

Actually, I've got a freshwater planted tank, and I add Iron every day. Plant growth is excellent.

I've had others aquariums with excellent macroalgae growth, and did never add iron. Anyway I will try, adding iron in my reef aquarium.

Is there any problem due overdosification?

[DennisRB]

From what have heard, its not dangerous. I would probably add less than what you do in your FW tank. Don't take my word for it, do a search or ask in Dr Rons forum (in the experts forums), I think he adds iron, so he may be able to help.


I have a FW tank too, and I add iron and nitrate to that, and there is no algae in it.

[Samala]

Ok - here's a quick warning from a Seachem rep to me on using iron in a marine environment:

"The amount of copper in Flourish is minimal - trace quantities for plants. It should be fine in marine systems. However, what is of primary concern is the amount of iron in Flourish. This will react quickly with the carbonates and fall out of solution. But, we have seen much higher toxicty of iron at lower levels in marine systems - particularly in the event of precipitation. So, the copper is not of issue but the iron may very well be of issue. Just a friendly warning."

I do NOT know at what concentrations we should worry about iron but I would not dose it at the same rate you might for freshwater.. not even close. This whole precipitation thing seems to be a very big concern for marine planted tanks actually.. Tom Barr has suggested nitrates and phosphates will fall out in marine tanks as well, along with some of the other micro's and Seachem points out iron in particular.

I was reading a paper on oceanic diatoms today (which are almost like algae.. some might argue they are microalgae) which reported on the receptors for N, P and Fe.. which got me wondering if iron was really important (or just well studied) to marine algae/plants. I think this may be my next project..

>Sarah

[DennisRB]

Sounds like a good project. Thanks Sarah.

There is a lot of info in this forum about adding iron, lots of people do it. You will probably find all you need to know by doing a search. Some people reported good growth when they added iron.

[Plantbrain]

Well, you folks found what I found several years ago.

I say things but folks scratch their heads and a few try it and see for themselves.

FW folks thought the same thing.........

Marine and /FW are different, one being the diatom bloom if you add too much PO4.

But we can add KNO3 without issue pretty much.
I do not know the upper limits, 5-15ppm seems fine though.

Traces can be dose rather high without issue.

Aeration(skimmers) and high Ca/KH are your friends!

You'll note a severe reduction in skimmate also after adding lots of plants/seaweeds.

So all it does is add CO2 stability.

I've been nagging marine folks to add NO3 and this is main cause for Caulpera melt in their refugiums.

Once the NO3 bottoms out, we see lots of what?

Cyano bacteria, blackout works well for that BTW with KNO3 dosing.

Or EM dosing + KNO3 additions thereafter.

Come to the plant fest and see these seaweeds and plants in person. Been going every year for the last 4.

Regards,
Tom Barr

www.BarrReport.com

[Samala]

EM dosing? Is that like the estimative index for marine? I've been reading the APD posts on Estimative.. good stuff.

Now, about low NO3 being related to cyanobacteria. I'm a little perplexed. I was able to grab a cyano outbreak in a low-NO3, high ammonia and high nitrite cycling environment. Also was relatively high PO4 since I was overdosing again to get that diatom/green bloom. I even started a thread wondering if cyano could be induced by the toxic N's along with a little too much P.

So you think its only related to low NO3 environment? My tank would fit the model I think.

>Sarah

[DennisRB]

Its probably not low N03 that does is directly, its the imbalance that low N03 can cause (in relation to phosphate etc).

[Samala]

Right.. which is "low NO3", when we're talking plants its pretty much a given that when a certain aspect of fert is said to be low that its considered low in proportion.. or out of balance. With marine we dont really know what the balance should be just yet. But realize that you might consider the system I am talking about to be a high N environment.. lots of nitrite and ammonia. And most of the things I am seeing for marine plants/micro/macroalgae do not separate out organic forms of N so far as looking at what the plants/various microalgae's prefer. I was just asking if low NO3, even in a high N environment, can instigate cyano. I think the excess amount of phosphate in this case may not have been really a key player. It may have just been a coincidental thing that the cyano bloomed just after ODing the phosphate just for fun.

>Sarah

[Plantbrain]

In a well run system, FW or Marine, the form of N is important.

Well run stable system have very low N measurable levels, even if a lot the N from uptake is from NH4.

The key there is the cycling time.

The NH4 is used up before the concentration has tiome to build up.

You never get a chance to measure it with a test kit.
This occurs in terrestrial soils and makes it difficult to follow the biogeochemical cycling.

So anything that messes with a plant/macro algae's ability to use NH4, will hurt the tank by favoring micro algae and BGA's.

They are highly responsive to change, plants/macros are slow and have higher nutrients needs than micro's.

So if the needs of the macros/plants are not met, then the NH4 will back up and the micro algae bloom.

N03 is far more benign and easier to measure than NH4.
So your test kits are skewed to see this rather than NH4.

Adding NH4 on purpose can be done to see this, don't do this unless you are willing to trash a tank FYI.

There are several forms of NH4 and organic complexes.
If the NO3 is bottomed out, the macros will not use up all the NH4, the macro's will also leak out organic reduced N as well..........

Then the algae/BGA bloom.
They don't need much and reduced N/NH4 is tasty high energy easy meal for them.

Larger plants are much less influenced by the form of N.

Additionally, if there is one parameter that we know can tell a plant or alage that someone is there and in high concentration, NH4 is a good one.

When it is low, we know there is something using it up.
When it's not, it's a good time to bloom.

Heterotrophs will still produce the same NH4, some 1/2 dead plants/macro's will leak out more NH4 and reduced N.

So if you do not focus on the NEEDS of the plants/seaweeds, then you'll favor the noxious microalgae.

The goal is good NH4 removal/growth for a balanced system for whatever loading rate you have for the tank(your bioload/plant load to the tank size).

This is why you cannot keep adding critters to supply all the needs of the plants/weeds in our tanks, the NH4 is overloaded and favors microalgae and you can a bloom.

Same deal with "curing" live rock, all the dying material produces a lot of reduced organic N.

After it's died off, and the pieces accilmated, then you can use it

Adding an inorganic source like NO3 from KNO3 is good since it supplies the weeds with a lot of N and in a bioavailable form.

You can also maintain a high residual for longer term supplies than say NH4.

PO4 will still induce diatoms and some green algae, unlike FW systems which can handle large amounts of PO4, 5ppm etc and have no algae response.

But you need to see which algae are produced by each parameter variation.

Then you can look at a tank and see what is wrong by looking at the micro algae they have.

This makes the balance in a tank easy to assess.
It also makes re setting a tank easy.

Lower PO4 dosing(but still dosing) is a wise idea.

Yes, EI works great for smaller Marine tanks.
But you need to change the water frequently.
Cheaper than Kalk reactors, dosing stuff etc and simpler.

Larger tanks need more care since they do not want to change weekly volumes and more tweaking is needed.

So...........if you want to use EI and dose more accurately, ah, there is a way to do this also.

Use liquid dosing.
Add KNO3 to a known volume of DI water. Use the solution in mls to dose very accurately the amounts needed for the tank.
You can add up to 0.1ppm of NO3 or higher accuracy per dose this way! And it's still simple.

If you use test ktis:
Calibrate your test kit against a known solution!

I have a spectrophotometer and they do this every time for the tested wavelength in question.

So my tested accuracy is very high, 0.01ppm of NO3, 0.01PO4, 0.01ppm NH4 etc. 10ppb is a good accuracy range for the hobby.

Regards,
Tom Barr

www.BarrReport.com

Barr's Marine planted tank competition 2K6?

[eleodes]

excuse me for butting in here with a very basic question, but when you refer to excluding nuisance microalgae by balancing nutrient ratios are hair algaes considered to be micros?

i started dosing with NO3 in response to declining macroalgae. the seaweeds are growing better now, but hair algae (not Bryopsis, the kind that just has unbranched strands growing from substrate) has become more of a problem.

so, is it possible to get rid of the hair algae by adjusting the ratios of nutrients?

[Plantbrain]

Probably not.
I scrub that off or use herbivores.
I've not found it to be fast growing.

I don't get it in macro algae/planted tanks
Even if I did, I can scrub it off fairly easily.

Regards,
Tom Barr